theodore lang



J. THEODORE LANG, WASHINGTON, DISTRICT OF COLUMBIA, ASSIGN'OR TO HIMSELF,v

E. H. 'A'SHCROF'L 0F BOSTON, MASSACHUSETTS, .AND S. S. FAHNESTOCK, OF ,WASH INGTON,*DISTRICT OF COLUMBIA.

Letters .Patent No. 79,767, dated' July 7, 186.8.

. IMPROVEMENT 1N eeuw-untermaternes.

To ALLJWHOM 1T MAY CONGERN:

Be it known that I, J. P. THEODORE LANG, ofthe city and county of Washington, in the District of Colum bia, have invented a new and improved Lathe for Cutting Screws; and I do hereby declare that the following is a. full `and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon in which likc'parts are designated by like letters in the several g-ures. l

The nature of my invention consists in so constructing a lathe for chasing s'crews as to secure the machinery against unnecessary weer; as well as accident, and secure 'the operating machinist against any mistakes in chasing over the same thread, and at the saine operation, saving a great deal of time.

To enable others skilled in the art to make and use myinvention, I will proceed to describe its construction vand operation.

4now revolved by the lead-screw E, and with it the In thedrawingsl y Figure 1 represents an elevation of my improved lathe.

Figure 3 is a modification of the governor, as shown in iig. 1, with certain details annexed, to be hereafter described; and Y i 4 Figure 2 represents scrcwswitb different threads, each having-its respective'governor.

A rcpresents an ordinary lathc-bed, supported as usual by legs, a..

B is the head and() the tail-block. v I r D is the carriage, moved by, the lead-screw'E, operated as usual by gear-wheels, b, c, and d.

F is the tool-post, on carria'geD, carrying the chasing or cutting-tool e. A

Fastened to the carriage D, and gearing into thelcad-screw'E, ig a worm-wheci, Gr, back ot' D, a side view of which is seen in iig. 3. This is connected by a stuchf, with the gcvernoril.-

Tb the lathe-bed A is attached a rack, I, ini which of'pinion works, operated as usual by a hand-wheel, J, -which moves the carriage when it is disconnected with the lead-screw E. i

K represents a rod of any desired material, to be threaded'or madeinto a scrcw,securcd between the latheccntres, and motion imparted to it as usual.

L is-a lever, having a slot,g, and pivotcd at h to the carriage D, the hooked or curved ond, z', made to catch into notches in thegovcrnor H.

4j is a slbt in the front plate of carriage D, in which works a smal! pinyin, which is fastened to a nut, M,

and which pin passes through the slotg in lever L.

The nut M has a thread to gear with lead-screw E. lhe operation of my lathe is as follows. vAfter the rod K is scoured between its centres, and motion imparted to it as usual, andthe cutting-tool@ adjusted, the lever L is moved in the position as shown in black lines in fig. 1. By means of pin m and slots g and j, the nut M, bythis operation, is thrown into gear with lead-screw E, and in this way thc carriage D is moved, andthe work of chasing is commenced and carried on. v

When a sullcicnt length has been cut, tnc tool `e is withdrawn from the rod K, and the lever L is pushed down into the position Aas shown by red lines in lig. I. This disconnects the nut M from lead-screw E, and the carriage D becomes stationary, when, by means of hand-wheel J and itspinion. in gear with rack I, the carriage is easily and rapidly run back by thc machinist.

As soon as the nut M is disconnected from the load-screw E, the worm-wheel G, which hns been at rest, is governor H. This governor is provided with a n umber of 'ntches on its rim, which, in a. certain position, will allownthe curved end, z', of lever L to slip `into the same.

-By this means the said lever is brought i v -\'nw, by 4bringing the nut M in gear with Jew To ellcct this, the machinist must press up the lever nto its first or normal position, necessary to start the carriage 4L, so that its point, z', 'bears against the rim oi' I-I whilst it is revolving, until one of thc slots 'mentioned comes into the desired position, and point z' passes into the interior corner of it. 4

The number ofthese slots in governor H depends upon the proportion of threads in screwsK and E; also upon the number oi' teeth in worm-wheel G. For instenceif the lead-'screwE has four threads to the inch, and the worm-wheel G has forty-eight teeth, it is evident that one revolutionof G will be equal to twelve inches lengt-h on'lead-screw E. If I now make twelve notches in thegove', nor I-I, the distance vbetween eachof them will be equal to one inch length on lead-screw il. Consequently, with this governor I can cut any whole number of'thrcalis to one inch, providing'tha-t I have changed the wheels b and ci so that their respective numbers of teeth are in the same proportion as the respective numbers' of threads en therod K and lead-screw E.

If, under the same circumstances, I wish to cut four and n. haii` threads to the inch, which makes nine threads to two inches, I make the number-voi' notches'lsnen, lthat the distancebetween each will correspond to two inches length on the lead-screw E. vThe number in this cose would be six, and it is to be understood that it would be y necessary to change the wheels b an'd Las before mentioned, and, as is always done, without the governor.

If desirable to cutn screw with three and two-thirds `threads tothe inch, the wheels and d Wcldbe changed accordingly, and therewould bc eleven threads on rod K, lcorresponding tothrce inches on lead-'screw E; consequently there would have to be four`notches in governorJ H.

' Following'thc same rule, for e screw 'of two and one-fifth -threads to theinch Aon rod K, it would 'be necessary to use a worm-wheelyG,with one hundred and twenty teeth, vand a governor, H, with six notches, because we would have eleven threads on rod K to rive inches length on lead-screw E, which is equal to twenty threads. I`Six tislesthesc answer to the six notches in the governor H. I

Figure l, in the drawing, .illustrates a case in which the rod'K has the same number of threads to the inch as lead-screw E, which is eight; consequently, wheels b :indd must have -each the same numberv of, teeth, the

worm-wheel G having twenty-four teeth, and the governor H six notches. The distance between the notches,

in this case, in governor H will answer to one-half inch length ou lead-screw E. Now,by'simply changing the wheels b and d to answer my purpose, I. can out any whole number of threads to the half inch on rod K. l

'lhe diiliculty of constructing very large worm-wheels, necessitated' by fractional threads, as, for instance,

in the case mentioned before, of two sind one-fifth threads to one inch`, can be overcome by.' amodication, shownin iig. 3. Here the governor has a number of notches corresponding to one inch length on lead-screw E, say, six notches in governor H, and twenty-four teeth 'on worm-wl1l Gr. This wormwheel is rigidly connected with the pinion N, which, by means of an intermediategearwheel O, moves another wheel', P, to which the governor H is fastened.

The numbers of teeth on wheelsN endl) must bear. the same4 proportion to each other as the numbers of threads ori-K and E, or the numbers of teeth on b and CZ. t

This modification can be substituted at pleasure for the first-described method. Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the nited States, is 4 The lever L, governor-plate H, and worm-wheel Gr, in combination with the feed-screw E. as and for the purpose set forth.

J. P. THEODORE LANG.

Witnesses S. S. FAHNEsTocK, Jos. I. Perron. 

